Currently, emergency lighting as required by most government regulations consists mainly of three basic types. The first type involves the use of a centralized cabinet containing batteries, a charger, an a.c. failure detector, a transfer switch, and a distribution circuit. This unit may also include an inverter to provide a.c. current instead of d.c. current to the lighting loads in case of emergency.
The second type of emergency lighting involves the use of small boxes which are placed around the walls of a building with contents similar to that described above. These boxes may have electric lamps mounted directly on them or the boxes may be located inside a cupboard or closet with the lamps mounted on a nearby wall, for example.
A third type of emergency lighting consists of ceiling fixtures mainly for suspended ceilings wherein the box containing the electrical components is mounted above the ceiling and the emergency lamps hang below the ceiling into the living space. The present invention is directed to this type of lighting equipment.
For optimum performance, it is usually required that ceiling fixtures of the type referred to above have their emergency lamp assemblies located above head weight with lens systems that can adequately illuminate the path of egress within a building.
As a general rule, architects and interior designers do not favor these requirements for several reasons. First of all, the lamp assemblies intrude into hallways, lobbies and other places where they may be required and do not blend with the design decor. Moreover, the lamp assemblies are exposed and can be easily damaged by accident or vandals requiring frequent replacement.
It is therefore an important object of the present invention to provide an improved emergency lighting fixture of the type which can be mounted in a ceiling.
Another object of the present invention is to provide such an improved emergency lighting fixture in which the lamp assemblies are totally concealed during the time that the unit is on stand-by service.
A more specific object of the present invention is to provide such an improved emergency lighting fixture in which the lamp assemblies automatically drops below the level of the ceiling upon the occurrence of a predetermined emergency and the lamps automatically turn on to illuminate selected paths of egress.